A Samarium “Soluble” Anode: A New Source of SmI₂ Reagent for Electrosynthetic Application

Abstract

An electrochemical method to prepare solutions of samarium diiodide in THF is reported. The simple electrolysis of a samarium rod provides a rapid and straightforward in situ synthesis of SmI2. The electrogenerated complex catalyzes various CC bond formations. The reagent is produced continuously (see scheme) and leads to efficient organic electrosynthesis with significantly smaller amounts of solvent than usually required.

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

“…608 Recently, reductive coupling of imines using a soluble samarium anode was reported (Figure 38C, right). 609,610 This electrode not only serves as the sacrificial anode to forestall the premature oxidation of radical anion intermediates; it also provides samarium salts that serve as mediators in the reaction.…”

“…While unmediated version of such reactions known as the electroreductive cyclization (ERC, vide infra ) have been rigorously examined by Little prior to 2000, several more recent reports have also emerged. ,− The scope and limitations of ytterbium mediated reductions have been extensively studied by Pletcher and co-workers . Recently, reductive coupling of imines using a soluble samarium anode was reported (Figure C, right). , This electrode not only serves as the sacrificial anode to forestall the premature oxidation of radical anion intermediates; it also provides samarium salts that serve as mediators in the reaction.…”

Electrode Materials in Modern Organic Electrochemistry

“…The procedures are remarkably straightforward and yield high purity complexes without the necessity for column chromatography. Similarly, Mellah demonstrated Sm II complexes could be efficiently prepared through the use of a sacrificial samarium anode, and are important catalysts …”

“…[222][223][224] Ther eaction is ap aired process (Figure 21 B), that is,t he ligand precursor is reduced on the cathode and the metal ions are produced on the anode.T he procedures are remarkably straightforward and yield high purity complexes without the necessity for column chromatography.S imilarly,M ellah demonstrated Sm II complexes could be efficiently prepared through the use of as acrificial samarium anode,a nd are important catalysts. [225][226][227]…”

Development in SmI2 Catalyzed Reactions

“…Electrochemical generation of SmI 2 was also demonstrated by Mellah et al ., where electrolysis was performed in an undivided cell using Sm metal as an anode, Pt as a cathode and tetrabutylammonium iodide was used an electrolyte [24] . They have proposed that in these experiments, Sm anode behaves as a ‘soluble’ electrode and generates Sm 2+ in the solution, which in the presence of tetrabutylammonium iodide produces SmI 2 .…”